Technical Abstract:
Assays based on the polymerase chain reaction (PCR) are now accepted methods for rapidly confirming the presence or absence of specific pathogens in foods and other types of samples. Conventional PCR requires the use of agarose gel electrophoresis to detect the PCR product; whereas, real-time PCR combines DNA amplification with fluorescent probe detection of the amplified target sequence in a closed tube format. Both conventional and real-time PCR and multiplex PCR assays have been developed for detection of E. coli O157:H7, Campylobacter species, simultaneous detection of E. coli O157:H7 and Salmonella species, and for specific detection of different E. coli serogroups based on unique gene sequences in the E. coli O antigen gene clusters. Microarrays, consisting of many probes complimentary to pathogen-specific gene sequences bound to a solid substrate, can hybridize multiple DNA targets simultaneously; therefore, microarrays have tremendous potential for detection, identification, and characterization of pathogens. Novel methods combining on-chip PCR of template DNA and simultaneous sequence-specific detection of amplification products on a solid phase show great potential for routine testing of bacterial pathogens in foods.